1. Field of the Invention
This invention relates to access control in general and particularly to access control for animals on a selective basis.
2. Description of the Prior Art
The prior art is described in U.S. Pat. No. 3,897,753 at column 1 lines 26 to 52; which description is incorporated herein by reference.
The prior art is well defined in the art-of-record of the parent patent application; being prior art U.S. Pat. Nos. 3,465,724 to Broadbent; 3,541,995 to Fathauer; 3,557,757 to Brooks; 3,516,575 to Moffitt; 3,180,321 to Aldinger; 3,557,758 to Lack; and 3,753,421 to Peck; wherein these prior art patents are incorporated herein by reference.